Apparatus for producing a light beam having a uniform phase front and distance measuring apparatus

Abstract

An apparatus including a frusto-conically shaped tube for transmitting light with internal reflection surfaces which diverge in the direction from input to output. Incident light from an LED or other substantially phase coherent source is mixed by internal reflection of rays incident at greater than a predetermined angle to minimize the non-uniform phase front and concentrate the beam to permit greater transmitted power. The apparatus finds particular utility in distance measuring instruments in which the output of the tube is directed to an object and the phase of the reflected light compared with the phase of the transmitted light to determine the distance.

What is claimed is: 
     
       1. An apparatus for measuring the distance between the apparatus and a remote target comprising: a soure of light;   an optical transmitting system including a tube for receiving at an input light from said diode within a given solid angle and an output, said tube having internal light reflecting surfaces which diverge from each other in the direction from input to output so that light entering at greater than a predetermined angle is reflected from said surfaces to minimize the non-uniform phase front, and increase the power;   means for modulating the light emitted from said diode;   photosensitive means for producing an electrical signal in response to incident light;   means for directing light from said tube to said target and directly to said photosensitive means and for directing light reflected from said target to said photosensitive means; and   means for determining said distance by comparing the phase of the signals produced by said photosensitive means.   
     
     
       2. A system as in claim 1, wherein said directing means includes a plurality of prisms and a front lens. 
     
     
       3. An apparatus as in claim 1, wherein said source is an LED. 
     
     
       4. An apparatus as in claim 1, wherein said system further includes a condensing lens between said source and tube and a collimating lens for collimating the light from said output. 
     
     
       5. An apparatus as in claim 1, wherein said tube is an electro-formed nickel tube clad with gold. 
     
     
       6. An apparatus as in claim 1, wherein said tube is 0.1 inches in length, and has an input diameter of 0.008 inches and an output diameter of 0.016 inches. 
     
     
       7. An apparatus as in claim 1, and wherein said tube is 0.02 inches in length and has an input diameter of 0.008 inches and an output diameter of 0.016 inches.